1. Field of the Invention
This invention relates to foot prostheses in general, and specifically to a prosthetic foot characterized by a unitary foot and heel construction, and an auxiliary ankle construction which permits the flexibility of the prosthesis to be selectively determined and easily changed.
2. Background of the Invention
Although many prosthetic devices have attempted to simulate the ambulation of a normal foot, very few of them are readily adjustable in terms of their performance characteristics. Adjustability is especially desirable among amputees who frequently participate in a variety of physical activities requiring varying levels of energy-storing and -releasing attributes.
Certainly, some prior art devices more nearly achieve the desired ease of adjustability than do others. For example, see my U.S. Pat. No. 4,547,913 for my invention relating to a “Composite Prosthetic Foot and Leg,” U.S. Pat. No. 4,822,363 for my invention relating to a “Modular Composite Prosthetic Foot and Leg,” my U.S. Pat. No. 5,181,932 for my invention relating to a “Foot Prosthesis Having Auxiliary Ankle Construction” and U.S. Pat. No. 5,290,319 for my invention relating to a “Prosthetic Foot Incorporating Adjustable Bladders” Also my U.S. Pat. Nos. 5,037,444 and 6,071,313 discloses a prosthetic foot device with similar preferred materials and methods of manufacture, and with corresponding benefits therefrom. Each of these patents is incorporated by reference herein.
Notwithstanding the valuable contribution and characteristics of my aforementioned patented foot prostheses and specifically the modularity thereof, the adjustment of those prostheses is relatively involved. Any adjustment of the performance characteristics of those prostheses basically requires the disassembly of a covering shroud (if present) and of structural members from each other and specifically from the pylon tube (through bolt, nut, and washer combinations, for example). After a new combination of structural members has been selected, it typically must similarly be reassembled. Disassembly of the prosthetic foot from the pylon requires a significant amount of time, effort, and money as it must be done by a prosthetist.
Other prosthetic foot devices are even less readily adjusted, and include U.S. Pat. No. 3,335,428 to Gajdos, which attempts to duplicate the skeletal and skin structure of a natural human foot, U.S. Pat. No. 2,075,583 to Lange, which incorporates a rubber form mounted in operative relationship with a rigid metallic core, and U.S. Pat. No. 4,645,509 to Poggi, which teaches a prosthetic foot incorporating a monolithic keel or beam of relatively massive proportions intended to react to the load of an amputee's body during walking, running, jumping, and the like and to release the resultant stored energy to create foot lift and thrust complementing the amputee's natural stride.
Moreover, the dynamic performance of many of these other prior art devices is relatively stiff and immediate, and generally cannot produce adequate plantar flexion during heel strike, while retaining sufficient stiffness for toe-off.